The present invention relates to an electronic control method and apparatus for an internal combustion engine, and more particularly to an improvement of an electronic ignition control method and apparatus as described and claimed in a copending U.S. patent application Ser. No. 872,778 filed on Jan. 27, 1978 in the name of Tadashi Hattori et al.
In such an electronic ignition control apparatus, it was proposed by the inventors that an optimum period of time for spark advance could be determined by the following equation (1) indicating a relationship between the optimum period of time for spark advance and an amount of air sucked into the engine. EQU T.sub.B =.alpha..multidot.Ga.sup.-.beta. ( 1)
where T.sub.B is the optimum period of time for spark advance and Ga is an amount of the sucked air, where each of .alpha. and .beta. is a parameter. However, it has been experienced that the optimum period of time for spark advance may not be precisely determined because the above-noted equation (1) is non-linear.